Further to my earlier answer, and for future use, I recommend you download this piece of FREE software called "Advanced System Care" from here:-
http://www.iobit.com/...edwindowscareper.html
Once downloaded and installed it will do all your cleaning up for you plus more. I have been using it for some time and I'm convinced my PC runs like new every day.
Run the "Maintain Windows" & "Diagnose System" features regularly. Just click on the button, then click "Scan". Let the utility do it's job and then click "Repair".